This invention represents an improvement to the invention set forth in U.S. Pat. No. 4,405,036 issued on Sept. 20, 1983 to Wener, et al. entitled "Seafloor Velocity and Amplitude Measurement Apparatus and Method" which is presented in FIG. 1 and discussed subsequently. However, prior to the filing of this patent, a patentability search was performed and the following patents were found:
______________________________________ Inventor Patent No. ______________________________________ F. K. Levin 3,193,045 G. B. Loper et al 3,219,968 J. I. Ewing et al 3,274,608 R. L. Sengbush 3,350,683 J. H. Cawley et al 3,441,901 Kenneth E. Burg 3,644,882 Hilmi F. Sagoci 3,831,136 Cook et al 4,016,531 William D. Jenkinson 4,079,353 ______________________________________
The 1972 patent to Burg (U.S. Pat. No. 3,644,882) relates to a marine acoustic velocity profiling system wherein a plurality of hydrophones are pulled rearwardly of the boat to receive acoustic reflections from the water layer which are generated by an acoustic source. The Burg system sequentially energizes the acoustic source to generate acoustical waves that travel downwardly into the water and into the shallow sediments below the water floor. The activation of the acoustical source is synchronized with the distance of travel by the boat. In the Burg approach, the acoustic source and the hydrophones are located in the same marine transverse plane remotely located above the water floor.
In the 1969 patent issued to Cawley et al (U.S. Pat. No. 3,441,901), a system of measuring sound velocity in water is set forth wherein a sonar transducer located underneath the boat generates acoustic waves which are subsequently detected by a hydrophone. The hydrophone is connected by means of a wire cable to the rear of the boat. Based upon the physical relationship between the hydrophone and the acoustic source, velocity of sound can be measured through the water.
The 1967 patent issued to Sengbush (U.S. Pat. No. 3,350,683) relates to a method of reducing the amplitude of water reverberations in marine seismograms. Like Burg, Sengbush utilizes a seismic source which in this case is attached to the bottom of the boat to produce seismic waves which travel downwardly to the ocean subsurface. The acoustic waves are then reflected upwardly into a detector which is pulled rearwardly of the boat. The detector in the Sengbush approach is maintained at a predetermined known depth. The maintenance of the detector at this depth minimizes reverberations.
The 1978 patent issued to Jenkinson (U.S. Pat. No. 4,079,353) relates to an offshore seismic surveying technique which utilizes a seismic source located beneath a boat generating acoustic waves for reflection into the subocean bottom. The reflected waves are sensed by a plurality of hydrophones which are pulled rearwardly of the boat (or to the side by another boat). The purpose of the invention is to locate scar zones on the floor of the bottom of the water.
The 1977 patent issued to Cook et al (U.S. Pat. No. 4,016,531) relates to a system for recording seismic reflection signals in a certain format. Cook et al utilizes a seismic source located beneath a boat which pulls a series of hydrophones. The invention relates to a technique for activating the acoustic source and processing the data received by the hydrophones.
The 1974 patent issued to Sagoci (U.S. Pat. No. 3,831,136) also relates to a method of analyzing seismic data generated from a boat carrying a seismic source and pulling a number of hydrophones on a towing cable.
The 1966 patent issued to Ewing et al (U.S. Pat. No. 3,274,608) also relates to a seismic profiler system wherein a first boat tows a seismic source for generating acoustic waves into the water which are then reflected into a hydrophone pulled by the same or a second boat. In the Ewing approach, a unique recording drum is utilized for profiling the seismic data.
The 1965 patent issued to Loper et al (U.S. Pat. No. 3,219,968) relates to a method and system for recording repetitive seismic signals from a boat carrying a seismic source beneath the boat and pulling a detector rearwardly of the boat coupled to a diving vane. The Loper approach relates to a particular technique in recording and analyzing the seismic data.
Finally, the 1965 patent issued to Levin (U.S. Pat. No. 3,193,045) relates to a boat containing both the seismic source and seismic detector located on the bottom of the boat. The purpose of the invention is to determine the depth of the water.
As will be presented in the discussion accompanying FIG. 1, it is believed that the approach set forth in FIG. 1 is more pertinent than any of the above prior patented approaches. Specifically, none of the above patents, uncovered in the search, set forth or even suggest an apparatus or method wherein the receiving hydrophones or sensors are actually located in the seafloor sediments.